System for cooling a sample in an apparatus for processing the sample

ABSTRACT

For cooled processing of a sample, a system for cooling the sample includes a holding device ( 22 ) for receiving the sample in a sample holder ( 20 ), as well as a cooling chamber ( 12 ) that surrounds the position (P) of the sample mounted on the holding device. Provided in the cooling chamber ( 12 ) is a window through which a tool receptacle ( 16 ) for receiving a tool (W) for processing the sample projects into the cooling chamber ( 12 ). The holding device ( 22 ) is coolable to a settable temperature by means of a fluid coolant, and ensures cooling of the sample. For this, a coolant, e.g. liquid nitrogen, flows through a coolant conduit of the holding device ( 22 ), which conduit is furnished with the coolant at the input end ( 31 ) and opens at the output end ( 41 ) into the cooling chamber ( 12 ), which in this fashion is filled with coolant gas.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority of Austrian patent application number A1762/2011 filed Nov. 29, 2011, the entire disclosure of which isincorporated by reference herein.

FIELD OF THE INVENTION

The invention relates to the processing of samples under cooledconditions. The invention further relates to a system for cooling asample for processing of the sample in a processing device.

BACKGROUND OF THE INVENTION

Processing apparatuses of the kind recited are manufactured for thepreparation of samples in particular for producing microtome sections.For this, for example, tissue samples to be investigated are embedded insynthetic resin and these samples are processed by means of a millingcutter into the shape of truncated pyramids (so-called “trimming”). Thesamples trimmed in this fashion are then sectioned in a microtome, withthe result that tissue sections having a thickness in the micrometer ornanometer range are obtained, which can then be investigated.

The Applicant has developed a unit suitable for such purposes, which isdescribed in EP 1 923 686 A2=US 2008-0115640 A1 and is already on themarket in an implementation under the designation “Leica EM TXP.” FIG. 1is a perspective view of this unit 100. Housed inside a cover 101 is aprocessing tool (not visible in FIG. 1; e.g. milling cutter, saw,grinding disc) with which a prepared sample to be processed (hereinaftera “sample”) is processed. The sample is located, for example, on asample holder (not shown) that is held by a sample receptacle 104 andprojects into cover 101 through an opening 105 thereof.

Cover 101 serves as an accidental contact protector during sampleprocessing. The lower part of cover 101 can moreover be used as acollection pan for polishing agent or other liquids that are directedonto the sample. The upper part of cover 101 is transparent andremovable; it is equipped with a switching element that interruptsrotation of the tool is the cover is removed.

Apparatus 100 comprises an observation device 103, for example astereomicroscope, that serves for viewing of the sample. If applicable,a measurement device that enables monitoring and/or measurement of thesample can be provided in the observation device. In a preferred variantof the invention, for example, a measuring eyepiece is used in thestereomicroscope; with this the sample itself, but also the progress ofthe processing action, can be accurately measured. Other systems, suchas e.g. video cameras and the like, can also be utilized as observationdevice 103.

To allow the sample to be cooled or lubricated during processing, unit101 can be equipped with a pump 106; via an inflow 107 a, a cooling orlubricating agent is delivered (from a reservoir container, notdepicted) to pump 106 and is conveyed via an outflow 107 b from pump 106to the sample.

Sample mount 104 is held in an arm 102 that is pivotable around ahorizontal axis S that extends perpendicular to the viewing direction ofobservation device 103. The pivoting of sample mount 104 by means of thearm allows the sample to be brought into different working positions,for example a measurement position, a processing position, and amonitoring position.

In the processing position (which is not shown in FIG. 1, but see FIG.3) the longitudinal axes of sample receptacle 104 and of the clampingapparatus for the processing tool lie substantially parallel to oneanother; in the unit shown, the two longitudinal axes are then locatedhorizontally. FIG. 1 depicts the monitoring position, in which samplereceptacle 104 is pivoted downward from the processing position and thesample surface is thus positioned exactly in the beam path ofstereomicroscope 103. This enables optical monitoring and analysis ofthe sample surface. The sample mount is rotatable in sample receptacle104 around its longitudinal axis, which extends perpendicular to axis S.The sample can thus be rotated by means of a rotary knob 108 in such away that all regions of the sample can be viewed throughstereomicroscope 103, and/or edges of the sample can be processed. Inthe additional measuring position, which is located, for example,approximately 20° above the processing position, precise measurement of,for example, the sample edges is possible using suitable measuringapparatuses in observation device 103.

This known unit of the Applicant is, however, like other conventionalunits of this kind, designed principally for processing hard samples orat least dimensionally stable samples, and not for processing samplesthat are soft at room temperature.

Processing of samples at low temperatures is described, for example, inthe Applicant's DE 40 28 806 C2=U.S. Pat. No. 5,299,481, which disclosesa microtome having a cooling chamber accessible from above. Cooling ofthe sample and of other cooled parts in the cooling chamber occurs hereexclusively by way of the gaseous cryogen with which the chamber ischarged. This prevents the deposition of moisture from the environmentonto the sample as ice (as a result of displacement by the gas), as wellas direct contact by the sample with cooling liquid; but it doesconsiderably complicate reliable setting of the sample temperature, andlimits the achievable cooling performance.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to make possible theprocessing of samples while the samples are cooled to a desired settabletemperature, while at the same time condensation of cooling liquidand/or moisture/ice on the sample and the sample environment is toremain precluded.

The stated object is achieved by a system for cooling a sample of thekind mentioned earlier, in that according to the present invention, theholding device can be cooled to a settable temperature by means of afluid coolant, the holding device comprising a coolant conduit throughwhich the coolant can flow and which for that purpose is furnished withthe coolant at the input end and opens into the cooling chamber at theoutput end; in addition, there is provided in the cooling chamber awindow through which a tool receptacle (of the sample processingapparatus), which serves to receive a tool for processing the sample, ispositionable in a manner projecting into the cooling chamber, and inthat context usefully is arranged without contact with the chamber.

The stated object is likewise achieved according to the presentinvention, in the context of the processing of samples under cooledconditions, by a method having the steps of:

-   -   receiving a sample to be processed, in a sample holder, onto a        holding device of the apparatus,    -   cooling the sample, and    -   processing the sample with the aid of at least one tool clamped        in the apparatus, such that sample cooling and sample processing        can of course in most cases be carried out in overlapping        fashion, the sample being cooled via the holding device, which        in turn is cooled by means of a fluid coolant to a settable        temperature, the coolant flowing through a coolant conduit of        the holding device, which conduit is furnished with the coolant        at the input end, and at the output end opens into a cooling        chamber that surrounds the sample during processing.

This approach allows the stated object to be achieved in surprisinglyefficient fashion. Cooling of the sample occurs not as a result ofcontact with coolant, but by heat transfer via the holding device. Theinterior of the chamber is filled only with coolant gas, which servesless for cooling than for the displacement of (as a rule, moist) ambientair, which avoids undesired condensation of moisture as ice. The tool assuch is not cooled (only indirectly via the coolant gas inside thechamber); cooling of the tool is dispensable, and results in asimplification of the configuration of the apparatus.

According to an aspect of the invention it is advantageous, as alreadyindicated, if the cooling chamber is designed to hold in its interior agas atmosphere that is constituted by the coolant and surrounds at leastthe sample. For this, after cooling the holding device the coolant canflow into the cooling chamber, and can create therein a cold gasatmosphere. Outflow of the gas can be enabled by the fact that thecooling chamber comprises, in addition to a window, an opening that isarranged on the upper side of the cooling chamber, although the coolingchamber is otherwise (i.e. aside from the aforesaid window and theopening) substantially closed off from the environment of the apparatus.“Substantially closed off” means here that the chamber comprises noopenings that, when the processing system is in the operating state,permit an inflow of ambient air or the like, although minor gaps, e.g.between movable parts, can be permitted if, for example, coolant gas canpenetrate through them to a sufficient extent and thereby suppress anyinflow of gases from outside. The cooling chamber can thus contain a gasatmosphere that is constituted by the coolant and surrounds at least thesample.

In order to allow reliable setting of the temperature of the sample onthe holding device, a temperature control system can be provided whichis designed to guide a liquid cryogen, in particular liquid nitrogen, inthe coolant conduit and evaporate it, and to allow only gaseous cryogento travel into the cooling chamber. A temperature sensor associated withthe temperature control system, which sensor is arranged at the outputend of the coolant conduit in order to monitor the passage of liquidcryogen, is suitable for preventing the cryogen from traveling in aliquid state into the cooling chamber.

For provision of the coolant, the coolant conduit can comprise at theinput end a coolant connector that is designed for connection of acoolant line of an external coolant vessel.

In a particularly advantageous refinement of the invention, the holdingdevice is arranged on a pivot arm that enables pivoting of the samplearound a pivot axis with respect to the tool receptacle. The pivot armcan be arranged outside the cooling chamber, such that a base of theholding device and/or the sample holder projects through an opening intothe cooling chamber. This opening can furthermore be closed off by ashield that is pivotable together with the holding device or the sampleholder. The previously mentioned coolant connector can moreover beoriented coaxially with the pivot axis. In a favorable embodiment, thearrangement of the coolant connector and pivot arm can be such that thepivot arm is held by a joint located to the side of the cooling chamber,and the coolant connector is arranged on that side of the coolingchamber which is located opposite the joint.

According to a further aspect of the invention, the system for samplecooling is removable, so that the cooling chamber together with theholding device and pivot arm is embodied in a sample cooling arrangementthat is removable from the sample processing apparatus. In the contextof a removable system, the cooling chamber can have a connectioninterface by way of which it is detachably mountable on theaforementioned apparatus for processing samples; the aforesaid window,through which a tool receptacle projects in the state mounted on theapparatus, is provided in this context inside the connection interface.

A further aspect of the invention relates to an apparatus for processingsamples of the kind recited earlier, in which apparatus the holdingdevice together with a cooling chamber is embodied in accordance withthe above-described system according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, along with further details and advantages, will beexplained below with reference to an exemplifying embodiment, namely asample processing apparatus having an arrangement for sample coolingthat is removable as an add-on unit, which arrangement is shown in theappended drawings. In the individual drawings, in schematic form:

FIG. 1 is a perspective view of a processing apparatus of the existingart;

FIG. 2 is a perspective view of the processing apparatus in accordancewith the exemplifying embodiment, having a mounted arrangement forsample cooling in the monitoring position for observation of the sample;

FIG. 3 shows the processing apparatus of FIG. 2 in the processingposition;

FIG. 4 is a perspective view of the arrangement in the removed state;

FIG. 5 is a detail view of the arrangement in the processing position;

FIG. 6 shows the processing apparatus as in FIG. 3, although here thearrangement is shown in a sectioned depiction (horizontal section);

FIG. 7 shows the arrangement as in FIG. 4, but in a sectioned depictionwith a horizontally extending section plane;

FIG. 8 is a perspective view of the cooling block of the arrangement;

FIG. 9 is a block diagram of the temperature regulator;

FIG. 10 is a sectioned view of the coolant pump; and

FIG. 11 shows the cooling chamber and cooling block in a furthersectioned view with a vertically extending section plane.

DETAILED DESCRIPTION OF THE INVENTION

The exemplifying embodiment described below represents a furtherdevelopment of the unit discussed earlier with reference to FIG. 1, inwhich the cover and sample mount are now embodied as a combinedlyremovable device with sample cooling. Be it noted that the embodimentshown is not to be understood as a limitation of the invention; oneskilled in the art can instead effect numerous variations andconfigurations of the invention.

Referring to FIGS. 2 and 3, a sample processing apparatus 10 accordingto the present invention with sample cooling is shown. In the Figures,the apparatus is equipped with a removable arrangement 11 for samplecooling, which at the same time contains a cooling chamber 12 thatsurrounds the sample during processing; the basic body of the apparatuscorresponds to the sample processing apparatus (e.g. of the “Leica EMTXP” type) described earlier with reference to FIG. 1, without cover andsample holder including the pivot arm. The description given above withregard to the apparatus of FIG. 1, in particular with regard to thevarious working positions and the associated processing of the sample,and to the observation device (stereomicroscope), thus applies in thesame fashion, aside from the sample cooling made possible according tothe present invention, to the apparatus according to the presentinvention, and reference is made in supplementary fashion to thedescription in the Applicant's EP 1 923 686 A2 (or US 2008/0115640 A1)and DE 10 2006 054 609 A1 (or US 2008/0118312 A1), both of which areherewith incorporated in their entirety as part of the presentdisclosure.

Apparatus 10 further comprises, as already mentioned earlier, anobservation device 13 (e.g. stereomicroscope) as well as a pump 14 withwhich the sample can be supplied with a liquid during processing; forprocessing with grinding discs, for example, alow-temperature-compatible liquid can be introduced as a grinding agentfor wet grinding. Tube 15 can be guided, on the upper side of thecooling chamber, through a separate opening in order to bring the liquidto position P of the sample. The lower part of chamber 12 can in turnserve as a collection pan for said liquid. It is significant in thiscontext that in the processing position, the sample and the tool areheld in substantially horizontal axes, since this allows excess grindingliquid to flow off quickly and decreases undesired deposition of solids.

Arrangement 11 for sample cooling is shown in FIG. 4 in the removedstate. The removable unit 11 performs essentially two tasks, for theimplementation of which two assemblies respectively corresponding to thetasks are provided:

-   1. Delimiting the processing space: A cooling chamber 12 comprises a    temperature-regulated outer wall and a shield 29 for sealing the    pivotable sample holder 20. An opening 43 on the upper side of the    chamber allows the prepared sample to be observed, and furthermore    serves to allow evaporated coolant gas to flow out in controlled    fashion.-   2. Prepared sample cooling: A pivot arm 21, which is pivotable    around the horizontal axis S (pivot axis) extending through the    cooling chamber, contains a holding device 22 for positioning a    sample holder 20 (FIG. 5). Holding device 22 is equipped with a    cooling block having flowthrough conduits for a coolant, preferably    a cryogenic liquid such as liquid nitrogen. The coolant is    evaporated and travels into the cooling chamber through an outlet    opening for the cold gas.

Arrangement 11 thus integrates the components of the system according tothe present invention for sample cooling into a system thatadvantageously is removable as a unit.

Arrangement 11 is mounted on apparatus 10 by means of a connectioninterface 17 that is embodied on chamber 12 and that surrounds a window47. Upon mounting onto apparatus 10, the chamber is positioned like acap over tool receptacle 16, so that the tool receptacle projectsthrough window 47 into the interior of chamber 12 but without touchingcomponents of the chamber. A tool mounted on tool receptacle 16 can thusmove freely inside window 47 to the extent necessary for processing thesample.

Arrangement 11 can be brought with the aid of pivot arm 21 into avariety of working positions, e.g. a processing position (FIG. 3) and amonitoring position (FIG. 2) for observing the prepared surface of theprocessed sample. Pivot arm 21 is fastened pivotably on processingapparatus 10 by way of a joint 23 that is arranged on one side ofcooling chamber 12. In the embodiment shown, joint 23 is mountedpermanently on processing apparatus 10, and a detachable connectingpoint is located between the joint and pivot arm (see FIGS. 4 and 7).

FIG. 5 is an enlarged partial view of arrangement 11 (mounted on theapparatus) in the processing position, the upper part of cooling chamber12 having been removed for clarity (the removed part is depicted withdashed lines). The previously mentioned tool receptacle 16, e.g. in theform of a collet chuck, is provided for receiving a processing tool (atposition W), and is rotatable around its longitudinal axis at a settablerotation speed, and positionable in the direction of that longitudinalaxis. In addition, the entire tool receptacle 16 can be displacedlaterally with respect to the position of the sample, e.g. for eccentricgrinding; actuation of this displacement motion occurs laterally on thehousing, as described in more detail in DE 10 2006 054 609 A1 or US2008/0118312 A1.

The sample is positioned at a predefined position P with respect to toolW or tool receptacle 16 with the aid of a sample holder 20. The sampleis symbolized here by its position P. Sample holder 20 is embodiedpreferably as a separate detachable component, and is fastened in aholding device 22 so that a sample present on sample holder 20 isentirely located in the interior of cooling chamber 12. Holding device22 is held by pivot arm 21 at a distance from pivot axis S and comprisesa base 25, oriented with respect to the pivot axis, which projectsthrough a passthrough opening 42 into chamber 12 and whose inwardlydirected end is set up for fastening and cooling of sample holder 20together with the sample.

Referring again to FIG. 2, arrangement 11 comprises a connector piece 30having a connector 31 for the delivery of liquid nitrogen (LN2) thatserves as a coolant. This connector 31 serves as a coolant connector fordetachable connection to a filling hose (plastic with insulation, ofknown type). The filling hose is in communication, for example, with anexternal coolant reservoir, e.g. an LN2 dewar.

FIGS. 6 and 7, in which arrangement 11 is shown in a sectioned depiction(with a horizontal section plane along pivot axis S), illustrate thelayout of conduit 24 for conveying the coolant or liquid nitrogen toholding device 22. The liquid nitrogen travels through connector piece30 via a hose part 33 into holding device 22. The connector piece 30,hose part 33, and holding device 22 are thermally insulated on theoutside.

Connector 31 is preferably embodied coaxially with pivot axis S, by thefact that is located rotationally symmetrically with its axis in pivotaxis S, and permits a rotation with respect to base part 32, attached tothe chamber, of connector piece 30. The result is that the hoseconnector remains stationary even in the context of rotation of thesample mount; the rotation in connector piece 30 occurs between basepart 32 and the attached part (FIG. 4) carrying connector 31. Theconnector connection is thereby decoupled from pivoting motions of pivotarm 21. This increases security, avoids damage to the filling hose uponpivoting as well as undesired motions of the coolant reservoir, andfacilitates stable positioning of the processing apparatus. Theconnector connection can be embodied with a non-rotating coolant hoseconnection of known type. Connector piece 31 is located on coolingchamber 12 preferably opposite the position of joint 23 of the pivotarm.

The liquid nitrogen flows along conduit 24 through holding device 22 ina cooling block 26, evaporates there, and travels as a cold gas throughbase 25 into cooling chamber 12. The pump for conveying liquid nitrogen(not shown) is regulated, with the aid of temperature sensors and usinga heating device (see below with reference to FIG. 9), in such a waythat only gaseous nitrogen travels into the cooling chamber. Gaseousnitrogen has two advantages: on the one hand, as a cold gas, it coolsthe chamber and processing tools. Secondly, the chamber is purged withthe dry gas, and the formation of ice crystals on the cold surfaces andon the sample is thus prevented. The gas emerges principally viaobservation opening 43 located on top.

FIG. 8 shows cooling block 26 in a separate perspective view; the leftside portion of the cooling block is removed in FIG. 8, and in additionthe upper side of the cooling block is removed, making visible themeandering layout of coolant conduit 24. A heating cartridge 34 ishoused in an orifice 44 of the cooling block, and a (first) temperaturesensor 35 in a second orifice 45. Multiple orifices are introduced intothe body of cooling block 26 on the upper and the lower side of thecooling block, the ends of each pair of orifices being connected bydepressions, with the result that a conduit extending back and forthbetween the left and right side of the cooling block is formed, servingas a coolant conduit 24. The depressions are closed off by side parts 28that are respectively attached on the left and right like a cover, thusproducing a linear conduit that here is split into two branches (upperand lower branch 24 a, 24 b). At the outlet end the two branches ofconduit 24 are guided through the base and lead to exit openings 41 atthat end of the base at which sample holder 20 is also attached. Theconduit thus opens at the output end (namely, with both branches) intocoolant chamber 12.

FIG. 9 is a block diagram of the control system for setting a desiredtemperature T of the sample by means of a temperature control loophaving heating system 34 and temperature sensor 35. This control loop,as well as thermal insulation with respect to the unit, enables adesired sample temperature to be set, in conjunction with a control unit(temperature control system 50) for setting the desired sampletemperature with a heat-up function after processing is complete. Theheating system also makes it possible to avoid condensation of ambientmoisture on the outer side of cooling chamber 12 and holding device 22.An LN2-compatible coolant pump 51 delivers liquid nitrogen, providedfrom coolant reservoir 37, to the cooling block.

Referring to FIG. 10 (sectioned view), pump 51 is [?implemented], forexample, by means of a membrane pump 52 that is embodied on cover plate38 of LN2 reservoir 37 with a pump head 57, immersed into the coolant,that is located in a manner immersed into the liquid nitrogen preferablyclose to the bottom of the LN2 reservoir. As a result of the designselected here, membrane pump 52 is located with its rubber membrane 53outside the LN2 reservoir and is separated from the valves in pump head57 and particular from the cold liquid. Membrane 53 is moved back andforth by an eccentric motor 54 (that moves around axis 55). The resultis to produce a moving gas column in pump tube 56 that connects membranepump 52 to pump head 57, and a (slight) positive and negative pressureis thus alternatingly generated in pump headspace 58 at the end of pumptube 56, with the result that two valves 61, 62 located in pump head 57alternatingly open and close in order to convey LN2. Each of the twovalves 61, 62 is embodied in the form of a ball having a conical sealingseat, and in the pressureless state is closed by the dead weight of therelevant ball. First valve 61 serves as an inlet valve; it connectsbetween an inlet opening 60 to the liquid space of reservoir 37 and pumpheadspace 58, and opens when there is negative pressure in the latter.Second valve 62, here referred to as a “delivery valve,” connects pumpheadspace 58 to a riser tube 59; it opens when there is positivepressure in pump headspace 58. When there is negative pressure in pumpheadspace 58, in a first step of a pumping operation liquid nitrogenflows through the inlet valve. In the next step, when a positivepressure is produced in pump headspace 58 by membrane pump 52, inletvalve 61 closes while delivery valve 62 is opened, and the liquid isforced into riser tube 59. When the pump headspace is once again broughtto negative pressure in a new cycle, delivery valve 62 closes again andthe cycle begins ab initio. Riser tube 59 leads through cover plate 38and opens at its upper end into a connector 63 for the coolant hose (notshown), which is connected to connector 31 of sample cooling arrangement11. The delivery capacity can thus be very accurately regulated by wayof the rotation speed of membrane pump 52; eccentric motor 54 of themembrane pump is operated, for example, as a stepping motor. At the sametime, the mechanism of pump head 57 is very robust and insensitive totemperature changes and icing.

Nitrogen delivery via coolant pump 51 is controlled as a function of thesetpoint temperature T. The rotation speed ranges of pump 51 are definedin the software of temperature control system 50 in such a way that foreach settable value of the setpoint temperature, the liquid nitrogenbecomes gaseous within the meanders of conduit 24. The resultingnitrogen gas is guided through openings 41 into chamber 12 and acts as aprotective gas against ice deposits on the cold surfaces in the interiorof the chamber. Heating system 35 is operated at only low output, andserves to increase the control accuracy and temperature consistency;without a heating system, the temperature would be several K below thesetpoint temperature.

A second temperature sensor 36, preferably arranged close to exitopenings 41, for example in a separate orifice 46, can be provided inorder to prevent liquid nitrogen from getting into the cooling chamber,said sensor. If the temperature at temperature sensor 36 drops below thetemperature of liquid nitrogen, or more precisely to a limit value justthereabove, the nitrogen is converted into the gas phase by additionalheating.

The chamber and other external surfaces can additionally be heated inorder to prevent the condensation of water.

FIG. 11 shows arrangement 11 in a sectioned view, with a horizontalsection through the longitudinal axis of the holding device. In thissectioned depiction, conduit 24 in cooling block 25 is visible inmultiply sectioned fashion because of its meandering layout.

Consistent with pivotability, a geometry of passthrough opening 42 forthe sample holder as an elongated or slot-shaped opening is useful. Ashield 29 that is prolonged in wing-like fashion along the pivotingdirection on both sides is provided on base 25 in order to close offopening 42 in the various working positions. Passthrough opening 42 isclosed off by shield 29 in every pivot position, and undesired emergenceof cold gas at this point is suppressed. Provided at the attachment ofshield 29 are wave spring washers 39 that counteract lifting of theshield away from the edge of opening 42.

With the aid of the invention it is possible to process samples that aretoo soft for processing at room temperature, by cooling them to atemperature at which said processing is possible, for example below anassociated glass transition temperature. A typical temperature range forprocessing is, for example, −120° C. to 170° C. Examples of samplematerials for which the invention enables processing are, for example,polymer- or rubber-based samples (e.g. structures made of wire or thelike embedded in rubber material), as well as biological samples.

The invention is not to be limited to the specific embodimentsdisclosed, and modifications and other embodiments are intended to beincluded within the scope of the invention.

PARTS LIST

10 Apparatus for sample processing

11 Sample cooling arrangement

12 Cooling chamber

13 Observation device/stereomicroscope

14 Pump

15 Tube

16 Tool receptacle

17 Interface

20 Sample holder

21 Pivot arm

22 Holding device

23 Joint

24 Conduit for coolant

25 Base (cooling block)

26 Cooling block

27 Body (of cooling block)

28 Side part (of cooling block)

29 Shield

30 Connector piece

31 Coolant connector

32 Base of connector piece

33 Hose part

34 Heating system/heating cartridge

35 First temperature sensor

36 Second temperature sensor

37 Reservoir

38 Cover plate of reservoir

39 Wave spring washers

41 Exit opening

42 Passthrough opening

43 Observation opening

44, 45, 46 Orifices

47 Window

50 Temperature control system

51 Coolant pump

52 Membrane pump

53 Membrane

54 Eccentric motor

55 Eccentric axis

56 Pump tube

57 Pump head

58 Pump headspace

59 Riser tube

60 Inlet opening

61 Inlet valve

62 Delivery valve

63 Connector for coolant hose

S Pivot axis

P Position of sample

W Tool

T Setpoint temperature

100 Apparatus (existing art)

101 Cover

102 Arm (pivot arm)

103 Observation device/stereomicroscope

104 Sample receptacle

108 Rotary knob for sample mount

105 Opening (in cover)

106 Pump

107 a, 107 b Inflow and outflow of pump

108 Rotary knob for sample mount

What is claimed is:
 1. A system for cooling a sample for processing of the sample in a processing device, comprising: a holding device configured to receive a sample for processing via a sample holder; a cooling chamber including a window, the cooling chamber surrounding the position of the sample mounted on the holding device; a tool receptacle configured to receive a tool for processing the sample, the tool receptacle being positionable through the window such that it projects into the cooling chamber; and wherein the holding device is coolable to an adjustable nominal temperature by a fluid coolant, the holding device comprising a coolant conduit through which the fluid coolant can flow, the coolant conduit having an input end configured to supply the fluid coolant and an output end that opens into the cooling chamber.
 2. The system according to claim 1, wherein the cooling chamber is configured to hold in its interior a gas atmosphere that is constituted by the coolant and surrounds at least the sample.
 3. The system according to claim 2, wherein the cooling chamber comprises, in addition to the window, an opening that is arranged on the upper side of the cooling chamber, while the cooling chamber is otherwise substantially closed off with respect to the environment of the apparatus.
 4. The system according to claim 1, wherein the holding device has a temperature control system configured to guide a liquid cryogen in the coolant conduit and evaporate it, and configured to guide only gaseous cryogen into the cooling chamber.
 5. The system according to claim 4, further comprising a temperature sensor associated with the temperature control system, the temperature sensor arranged at the output end of the coolant conduit in order to monitor the passage of liquid cryogen.
 6. The system according to claim 1, wherein the coolant conduit comprises at the input end a coolant connector configured to be connected to a coolant line of an external coolant vessel.
 7. The system according to claim 1, wherein the holding device is arranged on a pivot arm that enables pivoting of the sample around a pivot axis with respect to the tool receptacle.
 8. The system according to claim 7, wherein the pivot arm is arranged outside the cooling chamber, and wherein a base of the holding device and/or the sample holder projects through an opening into the cooling chamber.
 9. The system according to claim 8, wherein the opening is configured to be closed off by a shield that is pivotable together with the holding device or the sample holder.
 10. The system according to claim 7, wherein the coolant conduit comprises at the input end a coolant connector that is configured to be connected to a coolant line and is oriented coaxially with the pivot axis.
 11. The system according to claim 10, wherein the pivot arm is held by a joint located to a first side of the cooling chamber, and the coolant connector is arranged on a second side of the cooling chamber, the second side being located opposite the first side.
 12. The system according to claim 1, wherein the cooling chamber together with the holding device and pivot arm are detachably mountable as an add-on unit on an apparatus for processing samples, the cooling chamber being detachably connectable to the apparatus via a connection interface, and the window being provided in the connection interface.
 13. An apparatus for processing samples, comprising: a holding device configured to receive a sample holder, the sample holder configured to hold a sample to be processed; an observation device for observing the sample; a cooling chamber including a window, the cooling chamber surrounding the position of the sample mounted on the holding device; a tool receptacle in the cooling chamber configured to receive a tool for processing the sample, the tool receptacle being positionable through the window such that it projects into the cooling chamber; and wherein the holding device is coolable to an adjustable nominal temperature by a fluid coolant, the holding device comprising a coolant conduit through which the fluid coolant can flow and which can be supplied with the coolant at the input end and opens into the cooling chamber at the output end
 14. A method for cooled processing of a sample in an apparatus for processing samples, comprising the steps of: receiving a sample to be processed in a sample holder on a holding device of the apparatus, the holding device having a coolant conduit including an input end and an output end which opens into a cooling chamber that surrounds the sample during processing; cooling the sample via a fluid coolant flowing through the coolant conduit on the holding device; and processing the sample with at least one tool clamped in the apparatus.
 15. The method according to claim 14, wherein after cooling the holding device, the coolant flows into the cooling chamber and creates a cold gas atmosphere therein.
 16. The method according to claim 14, wherein the cooling chamber contains a gas atmosphere that is constituted by the coolant and surrounds at least the sample.
 17. The method according to claim 14, wherein a liquid cryogen is guided and evaporated in the coolant conduit of the holding device, such that only gaseous cryogen travels into the cooling chamber.
 18. The method according to claim 14, wherein the liquid cryogen is liquid nitrogen. 